Johannes Ullrich of the SANS Institute claims to have found malware infecting digital video recorders (DVR) predominately used to record footage captured by surveillance camera systems.
Oddly enough, Ullrich claims that one of the two binaries of malware implicated in this attack scheme appears to be a Bitcoin miner. The other, he says, looks like a HTTP agent that likely makes it easier to download further tools or malware. However, at the present time, the malware seems to only be scanning for other vulnerable devices.
“D72BNr, the bitcoin miner (according to the usage info based on strings) and mzkk8g, which looks like a simplar(sp.) http agent, maybe to download additional tools easily (similar to curl/wget which isn’t installed on this DVR by default),” Ullrich wrote on SANS diary.
The researcher first became aware of the malware last week after he observed Hiksvision DVR (again, commonly used to record video surveillance footage) scanning for port 5000. Yesterday, Ullrich was able to recover the malware samples referenced above. You can find a link to the samples for yourself included in the SANS Diary posting.
Ullrich noted that sample analysis is ongoing with the malware, but that it appears to be an ARM binary, which is an indication that the malware is targeting devices rather than your typical x86 Linux server. Beyond that, the malware is also scanning for Synology (network attached storage) devices exposed on port 5000.
“Using our DShield Sensors, we initially found a spike in scans for port 5000 a while ago,” Ullrich told Threatpost via email. “We associated this with a vulnerability in Synology Diskstation devices which became public around the same time. To further investigate this, we set up some honeypots that simulated Synology’s web admin interface which listens on port 500o.”
Upon analyzing the results from the honeypot, Ullrich says he found a number of scans: some originating from Shodan but many other still originating from these DVRs.
“At first, we were not sure if that was the actual device scanning,” Ullrich admitted. “In NAT (network address translation) scenarios, it is possible that the DVR is visible from the outside, while a different device behind the same IP address originated the scans.”
Further examination revealed that the DVRs in question were indeed originating the scans.
These particular DVRs, Ullrich noted, are used in conjunction with security cameras, and so they’re often exposed to the internet to give employees the ability to monitor the security cameras remotely. Unlike normal “TiVo” style DVRs, these run on a stripped down version of Linux. In this case, the malware was specifically compiled to run in this environment and would not run on a normal Intel based Linux machine, he explained.
This is the Malware sample’s HTTP request:
DVR Malware HTTP Request
The malware is also extracting the firmware version details of the devices it is scanning for. Those requests look like this:
Firmware Scan Request
While Ullrich notes that the malware is merely scanning now, he believes that future exploits are likely.
